A commercial building depreciates over decades under standard rules. That is a long time to recover the cost of an asset, and it means the deductions in early years are modest relative to what was spent.
A building is not one thing, though. It contains carpets, cabinetry, specialised electrical work, landscaping, parking, and fixtures — components with much shorter useful lives. Cost segregation identifies and separates them so each depreciates on its own schedule.
What changed in 2026
- Restored full first-year expensing amplified the benefit. With bonus depreciation back, reclassified short-life components can frequently be deducted immediately — see bonus depreciation.
- Studies became more accessible. Lower-cost offerings brought the technique to smaller properties.
- The passive loss constraint got more attention. Recognition that large deductions may be suspended rather than usable — see passive activity losses.
- Recapture consequences got better documented. The exit cost of acceleration became a standard part of the analysis.
What a study does
An engineering-based analysis examines the property and allocates its cost among components with different depreciation lives.
| Component type |
Typical life |
| Building structure |
Decades |
| Land improvements — paving, landscaping |
Intermediate |
| Personal property — carpets, fixtures, specialised systems |
Short |
| Land |
Not depreciable |
Moving cost from the long-life structure category into short-life categories accelerates the deductions substantially. With bonus depreciation available, short-life components may be deductible immediately rather than over several years, which concentrates a large deduction into the year of purchase or study.
The analysis requires engineering expertise and documentation to be defensible, which is why a proper study costs meaningful money and why a spreadsheet estimate is not a substitute.
What it does not do
It does not increase total deductions. You depreciate the same cost overall; you take more of it sooner. The benefit is entirely the time value of the earlier deduction, plus any rate difference if your bracket changes.
It does not remove recapture. Accelerated depreciation on short-life components is subject to recapture at ordinary rates when you sell, and it arrives sooner and larger than it would have. The deferral has a cost at exit — see depreciation recapture.
That combination means the benefit depends heavily on the holding period. A long hold gives many years of time value before recapture. A sale within a few years captures the acceleration and then immediately pays it back, which is close to self-defeating after the study cost.
The passive loss constraint
The consideration that most often makes a study less valuable than it appears.
Rental real estate is generally a passive activity, and passive losses can typically only offset passive income. A large accelerated deduction may therefore create a suspended loss rather than an immediate tax saving — it carries forward until you have passive income or dispose of the property.
That is not worthless; it is worth considerably less than an immediate deduction, and it changes the timing analysis entirely.
Exceptions exist, notably for those meeting real estate professional criteria, which are demanding and specific. Whether you qualify determines whether a study produces a current benefit or a suspended one, and it should be established before commissioning the study rather than after — see passive activity losses.
Common mistakes
- Commissioning a study without checking passive loss usability. May produce suspended losses.
- On a property you will sell soon. Recapture arrives before the benefit accumulates.
- Ignoring the study cost. It must be justified by the property value and holding period.
- Using an unsupported estimate. Defensibility depends on documentation.
- Forgetting the recapture consequence. Larger and sooner.
- Assuming it increases total deductions. It changes timing only.
- Not modelling the exit. The benefit depends on how long you hold.
FAQ
What property value justifies a study?
It depends on the study cost and your ability to use the deductions. Smaller properties have become viable as costs fell, and the passive loss question frequently matters more than the property value.
Can I do this on a property I already own?
Yes — a study on an existing property can allow catching up on missed acceleration, typically via a change in accounting method rather than amending prior returns.
Does it apply to residential rentals?
Yes, though residential structures already depreciate over a shorter life than commercial ones, so the relative benefit is smaller.
What if I do a like-kind exchange instead of selling?
A qualifying exchange defers the gain and the recapture, which preserves the benefit of acceleration. That combination is a common strategy — see like-kind exchange rules.
Where to go next
For the exit cost, read depreciation recapture. For whether the deductions are usable, passive activity losses, and for the immediate expensing that amplifies it, bonus depreciation.
This is general information, not tax advice. Cost segregation requires professional analysis; consult qualified advisers.